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  1. #21
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    Quote Originally Posted by GregSY View Post
    Microwave ovens...I read an interview with some woman who owned one of the first microwave ovens ever built. It was ancient but still worked. Turns out her father was at Raytheon and one of the engineers who 'invented' it. The one she had was like the 4th ever let out the doors....as you can imagine it cost a fortune and her mother had a heart attack when her father brought it home, so proud that his device was actually being sold on the market. Anyway, they attributed the reason it still worked to the fact that Raytheon had built it with an aerospace radar-quality tube, or some such. As the product became more refined and cost-reduced...they realized they could cut a lot of corners on that front.

    My sister-in-law had some old microwave...notable for the fact that she would routinely leave metal spoons in it to no detriment.
    my brother was on a submarine for a while and the microwaves would all get magnetron replacements before deplyment and they would noticably drop in power output. far as i know their decay rate is due to air leakage into the magnetron.

    older microwave ovens likely used much more expensive glass and glass to metal seal that don't leak (as we all know standard radio tubes can be good for 40+ years) rather than a cheap beryllium-aluminum oxide ceramic tube and a copper to ceramic metal seal.

    also i tend to agree with metalcarnage. an older transformer microwave is turned on by a single relay and the safe to turn on switch in the door (the transformer is shorted out by a second switch in the door)

    newer inverter microwaves may be turned on by software, no relays involved.

    if the relay turns on the fan turns on, there is no separate switch for the fan. there is usually two thermal switches, one on the magnetron and one on top of the oven cabinet. if you light something on fire in the micrwowave (such as a bag of microwave popcorn) it will burn for quite some time before the top of the oven chamber reaches 250F and you will.. (from experience) not be able to get the smell out of it. into the dumpster it goes.

  2. #22
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    Amana Radarange turns 53. it is the future...

  3. #23
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    jesus man! glad you didn't burn the shop down!!! OT Microwave oven melt down


    Sent from my iPhone using Tapatalk

  4. #24
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    Just as well. Get rid of the microwave because you don't want to eat radiated food. It will also keep you from buying all the ready-to-eat burritos.

  5. #25
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    Probably turned on by EMI from the welding.

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    Quote Originally Posted by MetalCarnage View Post
    This happened around the time of the daylight savings change? Is it possible that someone tried to change the time on the microwave and inadvertently set the timer to run instead and walked away? Let's see, thought he was changing the "time" to 11:00 and started it running for eleven hours straight. Makes more sense to me than starting on it's own.

    FWIW

    -Ron
    I was the only one here.

  7. #27
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    Quote Originally Posted by vanguard machine View Post
    jesus man! glad you didn't burn the shop down!!! OT Microwave oven melt down


    Sent from my iPhone using Tapatalk
    Me too!!!!

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  9. #28
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    Quote Originally Posted by Scottl View Post
    Probably turned on by EMI from the welding.
    I weld all the time and it never happened before.

  10. #29
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    Electrical surge? I have a light on a band saw. It was turned off and I was working along side it. Heard a bang and decided to investigate. Had a hard time finding the cause. One of the screws that was surrounded with the card board insulator blew a hole through the insulator and to the inner side of the Aluminum shell. Perfect size hole, very slight charring. No fire.

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    There have been particular models that do this.

    Bought a brand new Magxx Chex once on a close out sale. Biggest piece of crap I ever bought.

    Timer board started acting up within a couple of weeks. Bought a new timer board, repeated the same behavior a couple of weeks later.

    One of the more concerning things was that it would just start on its own and not shutoff unless unplugged. After doing some web searches, that was a normal occurrence for this model.

    I suspect that some of the re-badged consumer products coming out of our favorite manufacturing country do not always follow proper safety protocols. It seems that the brand names do not always bother in verifying what the are actually putting their name on.

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    Quote Originally Posted by Ziggy2 View Post
    It seems that the brand names do not always bother in verifying what the are actually putting their name on.
    I did q/c for a while on aluminum wheels. When I complained to the buyer (in the US) that we were not even getting 50% adherence on some of the features, some safety-related, I was told to shut up, if we complain too much they won't sell to us anymore.

    I quit shortly thereafter. What's the point ? And who is at fault ?

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    If I forget to attach the ground on my TIG welder, when I hit the arc it will raise the volume on my stereo system in the shop.

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    Quote Originally Posted by moonlight machine View Post
    I weld all the time and it never happened before.
    Filter caps designed to protect against EMI may have degraded with age. Without a proper post mortem it is difficult to tell but the circuits may have been weakened over time by surges, usage and even EMI from previous welding.

    Another thing many don't realize is that surge protective devices tend to degrade after multiple "hits" and eventually another surge can cause damage.

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    Quote Originally Posted by Ziggy2 View Post
    There have been particular models that do this.

    Bought a brand new Magxx Chex once on a close out sale. Biggest piece of crap I ever bought.

    Timer board started acting up within a couple of weeks. Bought a new timer board, repeated the same behavior a couple of weeks later.

    One of the more concerning things was that it would just start on its own and not shutoff unless unplugged. After doing some web searches, that was a normal occurrence for this model.

    I suspect that some of the re-badged consumer products coming out of our favorite manufacturing country do not always follow proper safety protocols. It seems that the brand names do not always bother in verifying what the are actually putting their name on.
    Went through this recently while trying to replace a basic (switch only) drip filter coffeemaker. Ended up buying a New Old Stock unit of the same make/model from an online vendor in order to be sure of TWO thermal fuses instead of a single one. I thought we resolved that issue decades ago yet coffeemakers are sold today that burn up. Read some of the reviews on Amazon. A few reviewers examined the failed units and found only one thermal fuse.

    I knew the old coffeemaker had two thermal fuses because I opened it to see what failed. The failure was the bimetal switch and since I couldn't find a reasonable cost replacement in single piece quantities a new unit was cheaper.

    PS: I once worked in Engineering/QC for a company that manufactures "over there" under licensed well known brand names. Often the problem is what happens after initial product approval as later production units mysteriously have missing or substituted parts. These discrepancies turn up in post mortems of customer returns. It's like a tug of war between the U.S. companies and the Chinese suppliers.

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    Quote Originally Posted by GregSY View Post
    If I forget to attach the ground on my TIG welder, when I hit the arc it will raise the volume on my stereo system in the shop.
    Adding in the micro wave get's this every time you stomp on the pedal
    YouTube

  18. #36
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    Quote Originally Posted by Scottl View Post
    .....

    PS: I once worked in Engineering/QC for a company that manufactures "over there" under licensed well known brand names. Often the problem is what happens after initial product approval as later production units mysteriously have missing or substituted parts. These discrepancies turn up in post mortems of customer returns. It's like a tug of war between the U.S. companies and the Chinese suppliers.
    Had that years ago, and not in production, but in approval samples.

    They used capacitors rated under the working voltage. Was just going to fail soon. Dinged them on that.

    Next sample had those OK, but another under-rated component that had been OK on sample #1. Another guaranteed failure. Dinged them on that new issue.

    Next sample had problem #2 corrected, but went BACK TO the original under-rated caps. Dinged them on that AGAIN.

    Purchasing then complained that we were just never going to approve anything, and had it taken out of our hands by upper management, who approved everything as-is without a question.

    We had QC issues of all sorts, in one case bad enough that we had to establish a rework production line in the warehouse. In that case the vendor actually changed a PC board layout without telling us. The change created a guaranteed failure under one condition that was going to occur sooner or later.

    I think the vendor orchestrated the entire deal, deliberately inserting old problems again, ones that could not be ignored, in hopes that the exact thing that did happen would happen: repeated samples rejected for cause, followed by management just blanket approving everything due to time crunch. In any case it worked out for them.

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  20. #37
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    Quote Originally Posted by JST View Post
    Had that years ago, and not in production, but in approval samples.

    They used capacitors rated under the working voltage. Dinged them on that.

    Next sample had those OK, but another under-rated component. Dinged them on that new issue.

    Next sample had problem #2 corrected, but went BAC TO the original under-rated caps. Dinged them on that AGAIN.

    Purchasing complained that we were just never going to approve anything, and had it taken out of our hands by upper management, who approved everything as-is without a question.

    We had QC issues of all sorts, in one case bad enough that we had to establish a rework production line in the warehouse. In that case the vendor actually changed a PC board layout without telling us. The change created a guaranteed failure under one condition that was going to occur sooner or later.
    We had the same pre-production experiences but we also found lots of relapses after a few months of production and throughout the products' lifespans. Without a vigorous approach to QC (and a generous customer service policy) manufacturing over there is, if you'll pardon the pun, Chinese Roulette.


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